H. morsus-ranae is classed as Critically Endangered in Spain, Endangered in Switzerland and Norway and Vulnerable in the United Kingdom. Otherwise, it is fairly widespread and abundant throughout its range.
It is a small floating plant resembling a small water lily. It bears small, three-petalled white flowers. The floating leaves are kidney-shaped and grow in rosettes on the water surface, with the roots hanging down into the water column but not normally touching bottom. Frogbit is fast growing and spreads rapidly by stolons, surviving the winter as dormant turions which rest on the bottom, rising again to the surface in spring.
Mass development of European Frogbit
Frogbit is native to Europe and parts of Asia, but it was introduced to Canada in the 1930s and has become invasive in eastern Canada and the northeastern USA, particularly around the Great Lakes. It is considered a pest in this region as it colonises waterways and forms dense masses of vegetation on the surface, threatening native biodiversity, although in its native areas it is rarely dominant.
H. morsus-ranae is classed as Critically Endangered in Spain and the Czech Republic, Endangered in Switzerland and Norway and Vulnerable in the United Kingdom. In France, it is protected at regional level in Alsace, Midi-Pyrénées, Provence-Alpes-Côte d'Azur, Rhône-Alpes and Limousin. Otherwise, there are no conservation measures in place or needed.